Using [11C]raclopride, a radioligand already demonstrated to be affected by dopamine (DA) release from methylphenidate and ampetamine (AMP) studies, this study will observe a decrease in Bmax measures with AMP challenge in both schizophrenic (SCZ) patients and normal controls. Through the appropriate PET imaging protocol it is expected that the magnitude of the decrease in Bmax to be greater in SCZ patients than in the controls. It is also expected that there will be no significant change in NMSP binding with AMP challenge in either. Each subject will first have Bmax measurement (2 PET scans) with raclopride or NMSP (saline), followed by a repeat of the same Bmax measurement (2 PET scans) but with AMP rather than saline. No patients will be taken off of medication for research purposes alone. Patients will be carefully selected who have either voluntarily or for purposes of clincal care been taken off medication. Normal will be recruited through the Nuclear medicine pool and will have to pass drug screening as well as tests done in the physical.